Decimal point indicator for slide rule

ABSTRACT

A numbered notched slide, 5, occupies a lengthwise bore, 4E, interior to the middle slide, 4, of the slide rule. Hook prods, 3A, 3B, attached to the cursor, 2, move this numbered notched slide. The addition of a transparent window, 4A, to observe numbers, spring, 6, and spring box, 4D, and openings in the middle slide, 4C, 4B, improve the device further. Proper operation of this improvement in the slide rule eliminates the need for the operator to carry the place of the decimal in his head while operating the slide rule.

[ DECIMAL POINT INDICATOR FOR SLIDE RULE [76] Inventor: Allen Noble, 14101 S. Woodland Rd., Shaker Heights, Ohio 44120 22 Filed: Mar. 27, 1973 21 Appl. No.: 345,363

Related US. Application Data [63] Continuation of Ser. No. 846,152, July 30, I969,

abandoned.

[52 US. Cl. .(235/643 [51] Int. Cl G06c 19/02 [58] Field of Search 235/61 DP, 64.3

[56] References Cited UNITED STATES PATENTS 2,363,642 11/1944 Cherney 235/643 [1 1] 3,834,614 Sept. 10, 1974 2,466,883 4/1949 Eckel ..235/64.3

2,526,730 10/1950 Christen 235/643 3,323,718 6/1967 Warner ..235/64.3

Primary Examiner-Lawrence R. Franklin [5 7] ABSTRACT 2 Claims, 17 Drawing Figures DECIMAL POINT INDICATOR FOR SLIDE RULE This application is a continuation of Ser. No. 846,152, filed July 30, 1969, now abandoned.

This invention is directed to a slide rule, and more specifically to an improved slide rule having a new and novel decimal point figuring means.

An object of this invention is to provide a slide rule which relieves the necessity of the operator retaining the position of the decimal in his head while operating the slide rule.

Another object is to provide a slide rule which reduces the amount of mental labor required to make a calculation.

A further object is to provide a slide rule which reduces the number of errors made in calculation and particularly the number of errors made in placing the decimal point.

Still another object is to provide a slide rule which is sturdy, simple and reliable in operation, and also simplifies the calculation point.

Other features and advantages will become readily apparent when considered in view of the followingdescription and drawings in which.

In the drawings:

FIG. la, is the .front view of the left half of the slide rule of this invention.

FIG. 1b, is the front view of the right half of the slide rule of this invention.

FIG. 2, is a section view taken thru line 2-2 of FIG. la, showing the end of the slideyrule of this invention.

process, particularly the decimal FIG. 3A, is a section view of the left half of the slide rule of this invention, where said FIG. 3Ais taken thru line 3-3 of FIG. 2.

FIG. 3B, is a section view of the right half of the slide rule of this invention where said FIG. 3B, is taken thru line 3-3 of FIG. 2.'

FIG. 4, shows part of FIG. 3A, with the hook prods, 3A, 3B, reversed.

FIG. 5A, shows the front view of the left half of the notched numbered slide, 5.

FIG. 5B, shows the front view of the right half of the notched numbered slide, 5.

FIG. 6A, shows the'side view of the left half of the notched numbered slide, 5.

FIG. 6B, shows the side view of the right half of the notched numbered slide, 5.

FIG. 7A, shows the front view of the left half of the middle slide, 4.

FIG. 7B, shows the front view of the right half of the middle slide, 4.

FIG. 8A, shows the side view of the left half of the middle slide, 4.

FIG. 8B, shows the side view of the right half of the middle slide, 4.

FIG. 9A, shows the back view of middle slide, 4.

FIG. 9B, shows the back view of the right half of the middle slide, 4.

FIG. 10, shows the right end of the middle slide, 4.

the left half of the slide, 4; a notched numbered slide, 5; and a spring, 6.

the positions of The hook prods, 3A, 3B, are attached to the cursor, 2, by means of hinges, 2A, 2B. The middle slide, 4, has the following features: a number observing window, 4A; hook prod openings, 48, 4C,; a spring box, 4D; a lengthwise bore, 4E; and stars to the right and left of the indexes, 4F, 4G.

This invention is designed such that the following facts are true.

Fact 1, only one of the numbers, 5B, is visible thru the number observing window, 4A, while the numbered notched slide, 5, remains stationary with respect to the middle slide, 4.

Fact 2, the distance between notches, 5C, is less than the distance between the indexes and the star 41, 4H.

Fact 3, the distance between notches, 5C, equals the distance between number, 5D.

If the right hook prod, 3A, is in the position shown in FIG. 3, the operator may cause the numbered notched slide, 5. to move right one notch with respect to the middle slide, 4. Upon this rightward movement of the numbered notched slide the following events take place:

Event 1, movement of tip of right hook prod, 3C,

along face, 4.], of middle slide, 4.

Event 2, movement of tip of right hook prod, 3C,

down ramp, 4K, leading to hook prod opening.

Event 3, movement of tip of right hook prod, 3C,

down the incline of notch, 5E.

Event-4, contact of hook prod, 3A, with vertical face of notch, 5F.

Event 5, rightward movement of numbered notched slide, 5, and upward movement of tip of spring, 6A.

Event 6, contact of tip of spring, 6A, with tip of notch, 56.

Event 7, continued rightward movement of notched numbered slide, 5, and downward movement of tip of spring, 6A.

Event 8, contact of hook prod, 3A, with outside of hook prod opening, 4L; return of spring, 6; to original position; an end of movement of notched numbered slide, 5; and coincidence of hairline, 2C, and star, 4F.

In likewise manner the operator may cause leftward movement of one notch, when the left hook prod, 3B, is in the position shown in FIG. 4.

The two following example problems will illustrate how the operator uses this invention.

To solve this first example problem,

The operator executes the following steps:

Step 1,- the operator counts the total number of figures to the left of the decimal in the numerator. In this instant first example, the operator counts 2 figures for 95, 2 figures for 25, l figure for 5.6, 2 figures for 10 for a total of 7 figures.

Step 2, the operator counts the total number of zeroes between the decimal point and the first figure of the number in the numerator. In this instant first example the operator counts 1 zero for 0.045, for total of '1 zero.

Step 3, the operator subtracts the result of step 2 from the result of step I. In this instant first example the operator subtracts 1 from 7 to obtain 6.

Step 4, the operator counts the total number of figures to the left of the decimal in the denominator.

Step 6, the operator subtracts-the result of step from step 4.'In this instant first example the operator subtracts 3 from 2 to obtain l. I

Step 7, the operator'subtracts the result of step 6 from step 3. In this instant first example, the operator subtracts 1 from 6 to obtain 6--(l) which equals 7. I

' Step 8, the operator puts the hook prods, 3A, 3B, in

the multiply position shown in FIG. 3 of the drawings and also places the notched numbered slide, 5, in a position such that the number zero, 5H, shows thru the window, 4A.

Step 9, the operator multiples normally using the C1 and D scales remembering; to'place the hairline, 2C, of the'cursor, 2, over the star,"4F, before placing said hairline, 2C, over the right index. In this instant first example, the operator makes the hairline, 2C, of the cursor, 2, and the 950 mark on the D scale, coincide, by moving the cursor; makes the 25 mark on the Cl scale and the hairline, 2C, of the cursor, 2, coincide by moving the middle slide, 4; makes the hairline, 2C, of the cursor, 2, and left index of the Cl scale coincide by moving the cursor, 2, causing the hairline to coincide with the 238 mark on the'D scale; makes the hairline, 2C, of the cursor, 2, and the 45 mark on the C1 scale coincide by moving the middle slide, 4; makes the left index of the Cl scale and the hairline, 2C, of the cursor, 2, coincide by moving the cursor, causing the hairline, 2C, to coincide with the 107 mark on the D scale; makes the 56 mark on the Cl scale and the hairline, 2C, of the cursor coincide by moving the middle slide, 4; moves the hairline, 2C, of the cursor to the right star, 4F; causing the number shown in the window, 4A, to change from 0 to l; makes the right index of the Cl scale and the hairline, 2C, of the cursor, 2, and the 600 mark on the D scale to coincide; does not move the middle slide, 4, since the hairline, 2C, of the cursor, 2, is already on the mark of the slide rule; moves the hairline, 2C, of the cursor, 2, to the star, 4F, causing the number shown in the window to change from 1 to -2; makes the right index of Cl scale and the hairline, 2C, of the cursor coincide, again causing the hairline, 2C, of the cursor, 2, and the 600 mark on the D scale to coincide.

Step 10, the operator puts the hook prods, 3A, 3B,

in position shown in FIG. 4 of the drawings.

Step 11', theoperator divides normally, using the C and D scales, remembering to place the hairline, 2C, of the cursor, 2, over the left star, 4G, before placing it over the left index. In this instant first example, the operator makes the 32 mark on the C scale coincide with the hairline, 2C, of the cursor, 2, said hairline coinciding with 600 mark on D scale, by moving the middle slide, 4, moves the hairline, 2C, of the cursor to the left star, 4G, causing the number shown in the window, A, to change from 2. to -l; makes the hairline, 2C, of the cursor, 2, and left index of the C scale coincide, by moving the cursor, causing the hairline, 2C, and 187 mark on the D scale to coincide; makes the hairline, 2C, of the cursor, 2, and the 42 mark on the C scale coincide by moving the middle slide, 4; makes the right index of the C scale and the hairline, 2C, of the cursor, 2, to coincide; makes the hairline, 2C, of the cursor, 2, and 5.3 mark on the C scale coincide by moving the middle slide, 4; makes the right index of the C scale and the hairline, 2C, of the cursor, 2, coincide by moving the cursor, 2, causing the hairline, 2C, of the cursor, 2,

and 840 mark on the D scale to coincide.

Step 12, the operator adds the result of step 7 to the number shown in the window, 4A, to obtain the number of figures to the left of the decimal if positive or the number of zeroes between the decimal point and the first figure if negative. Inthis instant first example the operator adds I to 7 to obtain 6. From this, the operator knows the final answer is 840 with six figures to the left of the decimal or 840,000.

To solve the second example,

The operator executes the following steps:

Step 1, the operator counts the total number of figures to the left of the decimal in the numerator. In this instant second example, the operator counts 2 figures for 26 for total of 2 figures.

Step 2, the operator counts the total number of zeroes between the decimal point and the first figure in the numerator. In this instant second example, the operator counts 2 zeroes for 0.0025, 1 zero for 0.067, for a total of 3 zeroes.

Step 3, the operator subtracts the result of step 2 from the result of step 1. In this instant second example, the'operator subtracts 3 from 2 to obtain I.

Step 4, the operator counts the total number of figures to the left of the decimal in the denominator. In this instant second example, the operator counts 2 figures for 56, 1 figure for 4.4, for a total of 3 figures.

Step 5, the operator counts the total number of zeroes between the decimal point and the first figure in the denominator. In this instant second example, the operator counts 1 zero for 0.01 for a total of 1 zero. 1

Step 6, the operator subtracts the result of step 5 from the result of step 4. In this instant second example, the operator subtracts 1 from 3 to obtain 2.

Step 7, the operator subtracts the result of step 6 from the result of step 3. In this instant second example, the operator subtracts 2 from 1 to obtain (l(2)) or 3.'

Step 8, the operator places the hook prods, 3A, 3B, in the multiply position shown in FIG. 3 and also places the numbered notched slide, 5, in a position such that zero, 5H, shows thru the window, 4A.

Step 9, the operator multiplies normally with the Cl and D scales, remembering to place the hairline, 2C, of the cursor, 2, over the star, 4F, before placing said hairline, 2, over the right index. In this instant second example, the operator makes the hairline, 2C, of the cursor, 2, and the 25 mark on the D scale coincide; makesthe hairline, 2C, of the cursor, 2, and the 67 mark on the C1 scale coincide by moving the middle slide, 4; makes the left index of the C1 scale and the hairline, 2C, of the cursor, 2, coincide by moving the cursor, 2, causing the hairline, 2C, of the cursor to coincide with the 170 mark on the D scale; makes the hairline, 2C, of the cursor, 2, and the 26 mark on the Cl scale coincide by moving the middle slide, 4; makes the hairline, 2C, of the cursor, 2, and the star, 4F, coincide causing the number observed thru the window, 4A, to change from 0 to l; makes right index of C1 scale coincide with the hairline, 2C, of the cursor, 2, by moving the cursor causingthe hairline, 2C, of the cursor to coincide with 438 mark on the D scale.

Step 10, the operator puts the hook prods, 3A, 3B,

in position shown in FIG. 4 of the drawings.

Step 11, the operator divides normally with the C and D scales, remembering to place the hairline, 2C, of cursor, 2, over the star, 46, before placing said hairline, 2C, over the left index. ln this instant second example, the operator makes the mark on the C scale, which is the left index, coincide with the hairline, 2C, of the cursor, 2, by moving the middle slide, 4; makes the left star, 46, and the hairline, 2C, of the cursor, 2, coincide causing the number shown in the window 4A, to change from 1 to 0; makes left index of the C scale and hairline, 2C, coincide by moving the cursor, 2;makes the 525 mark on the C scale coincide with the hairline, 2C, of the cursor, 2; makes the hairline, 26, of the cursor, 2, and right index coincide, causing 835 mark on the D scale and the hairline, 2C, of the cursor, 2, to coincide; makes the hairline, 2C, of the cursor, 2, and the 56 mark on the C scale coincide by moving the middle slide, 4; makes the hairline, 2C, of the cursor, 2, coincide with the left star, 46, causing the number shown thru the window to change from 0 to 1; makes the hairline, 2C, of the cursor, 2, and left index coincide by moving the cursor, causing the hairline, 2C, of the cursor, 2, and the 149 mark on the D scale to coincide; makes the hairline, 2C, of the cursor, 2, and 44 mark on the C scale coincide by moving the middle slide, 4; makes the hairline, 2C, of the cursor and right index of the C scale coincide by moving'the cursor, 2, causing the hairline, 2C, of the cursor, 2, and the 340 mark on the D scale to coincide.

Step 12. The operator adds the result of step 7 to the number shown in the window, 4A, to obtain the number of figures to left of the decimal if positive or the number of zeroes between the decimal point and the first figure if negative. In this instant sec- 6 ond example, the operator adds 1 to 3 to obtain 2. From this the operator knows the final answer is 340 with two zeroes between the decimal point and first figure or 0.00340. That the above method of using this invention will always work, can be seen by noting that the expression of N1 where N1 is-any number, N1 is any number between 0.1 and 1.0, and

B is an integer.

B clearly is the number obtained in step 7 of example problems one and two This expression,

(N11N31 5 2 4 N61 N! where N is a number between 0.1 and is a integer.

Since a equals the number of times the hairline of the cursor is placed on the left index while dividing, minus the number of times the hairline of the cursor is placed on the right index while multiplying, a is clearly equal to the number shown in the window, 4A, at the completion of step 11 of both example problems.

Clearly then which is the result of step 12 of both example problems a+b is clearly the number of figures to the left of the decimal if a+b is positive or the number of zeroes between the first figure and the decimal if a+b is negative.

From the foregoing it will be noted that this invention cooperates with the natural action in working the slide rule, relieves the operator of the necessity of remembering the position of the decimal while operating the slide rule; is simple in operation, and rugged in construction.

While the instant invention has been disclosed with reference to a particular embodiment thereof, it is to be appreciated that the invention is not to be taken as limited to all the details thereof as modification and variations thereof may be made without departing from the spirit or scope of the invention.

What is claimed is:

l. A decimal point indicator for a slide rule comprising a cursor, two hook prods attached to said cursor, a middle slide having a base, hook prod openings, and a window, another slide having numbers thereon and notched adjacent its ends and slidable in said bore.

2. The invention is defined in claim 1 where the middle slidehas a spring box attached and a spring interior to said spring box. 

1. A decimal point indicator for a slide rule comprising a cursor, two hook prods attached to said cursor, a middle slide having a base, hook prod openings, and a window, another slide having numbers thereon and notched adjacent its ends and slidable in said bore.
 2. The invention is defined in claim 1 where the middle slide has a spring box attached and a spring interior to said spring box. 